#define _CRT_SECURE_NO_WARNINGS 1
class Solution {
public:
    string addStrings(string num1, string num2)
    {
        int end1 = num1.size() - 1;
        int end2 = num2.size() - 1;
        int next = 0;
        string ans;
        while (end1 >= 0 || end2 >= 0)
        {
            int val1 = end1 >= 0 ? num1[end1] - '0' : 0;
            int val2 = end2 >= 0 ? num2[end2] - '0' : 0;
            int sum = val1 + val2 + next;
            next = sum / 10;
            sum = sum % 10;
            ans.insert(ans.begin(), 1, sum + '0');
            end1--;
            end2--;
        }
        if (next == 1)
        {
            ans.insert(ans.begin(), 1, '1');
        }
        return ans;

    }
};